This invention relates to hydrocarbon conversion processes employing reducible metal oxide compositions. One particular application of this invention is a method for converting methane to higher hydrocarbons. Another particular application of this invention is a process for the oxidative dehydrogenation of hydrocarbons, especially a process for the oxidative dehydrogenation of paraffinic hydrocarbons to the corresponding mono-olefins.
A central aspect of the presently claimed invention is the catalyst composition employed in such hydrocarbon conversion processes. In one particular aspect, the present invention relates to compositions comprising alkaline earth promoted reducible metal oxides (especially reducible oxides of manganese). In one still more specific embodiment, this invention relates to compositions comprising oxides of Mn, alkaline earth metals, alkali metals and boron.
Recently, it has been discovered that methane may be converted to higher hydrocarbons by a process which comprises contacting methane and an oxidative synthesizing agent at synthesizing conditions (e.g., at a temperature selected within the range from about 500.degree. to about 1000.degree. C.). Oxidative synthesizing agents are compositions having as a principal component at least one oxide of at least one metal which compositions produce C.sub.2 + hydrocarbon products, co-product water, and a composition comprising a reduced metal oxide when contacted with methane at synthesizing conditions. Reducible oxides of several metals have been identified which are capable of converting methane to higher hydrocarbons. In particular, oxides of manganese, tin, indium, germanium, lead, antimony, bismuth, praseodymium, terbium, cerium, iron and ruthenium are most useful. See commonly-assigned U.S. Pat. Nos.4,443,649 (Mn); 4,444,984 (Sn); 4,445,648 (In); 4,443,645 (Ge); 4,443,674 (Pb); 4,443,646 (Bi); 4,499,323 (Pr); 4,499,324 (Ce); and 4,593,139 (Ru), the entire contents of which are incorporated herein by reference. See also commonly-assigned U.S. patent application Ser. No. 06/666,694 (Fe) the entire content of which is incorporated herein by reference.
Commonly-assigned U.S. Pat. No.4,554,395 discloses and claims a process which comprises contacting methane with an oxidative synthesizing agent under elevated pressure (2-100 atmospheres) to produce greater amounts of C.sub.3 + hydrocarbon products.
Commonly-assigned U.S. Pat. No.4,560,821 discloses and claims a process for the conversion of methane to higher hydrocarbons which comprises contacting methane with particles comprising an oxidative synthesizing agent which particles recirculate between two physically separate zones--a methane contact zone and an oxygen contact zone.
As noted, the reaction products of such processes are mainly ethylene, ethane, other light hydrocarbons, carbon oxides, coke and water. It would be beneficial to these oxidative synthesis processes to reduce selectivities to carbon oxides and coke.
Hydrocarbon conversion processes employing the composition of this invention are characterized by relatively severe reaction conditions and by the formation of coproduct water. Thus, hydrothermal stability at elevated temperatures (e.g., 500.degree. to 1000.degree. C.) is an important criterion for the compositions. Moreover, uses contemplated for the present compositions require catalysts which are rugged, attrition-resistant, and stable at high temperatures. It is also desirable that the compositions are able to operate effectively for relatively long periods while cycling between oxidized and reduced states.
An object of the present invention is a composition and process for hydrocarbon conversion processes, especially for processes characterized by the formation of byproduct water. A related object is a rugged, stable, attrition-resistant oxidant composition for such processes.
Another object of the present invention is a composition and process for converting methane to higher hydrocarbons, especially for processes characterized by the formation of byproduct water. A related object is a rugged, stable, attrition-resistant oxidant composition for such methane conversion process.
Still another object of the present invention is a composition and process for the oxidative dehydrogenation of hydrocarbons. A related object is a rugged, stable, attrition-resistant oxidant composition for such processes. Another related object is a composition and process for the oxidative dehydrogenation of paraffinic hydrocarbons to form the corresponding mono-olefins.
Other objects, aspects and advantages of the invention will be apparent to those skilled in the art upon studying the specification and the appended claims.